Two-cycle crankcase compression engine



June 22, 1948. .1. w. SMITH TWO-CYCLE CRANKCASE COMPRESSION ENGINE 3Sheets-Sheet 1 Filed Jan. 2, 1946 INVENTQR Jay W aim/#7 ATTORNE YS June22, 1948. J. w. SMITH 2,443,838

TWO-CYCLE CRANKCASE COMPRESSION ENGINE Filed Jan. 2, 1946 3 Sheets-Sheet2 FY55: 7. 37 Hg :2

INVENTOR Jay V/m/fh qemil June 22, 1948. J. w. SMITH 2,443,838

TWO-CYCLE CRANKCASE COMPRESSION ENGINE Filed Jan. 2, 1946 3 Sheets$heet3 IN V E NTO R Jay mas/mm Patented June 22, 1948 Jay W. Smith, Algonac,Micln, Craft Corporation, Algonac,

tion of Delaware asaisnor to Chris- Micln, a corpora- Applicationlanuary z, 1946, Serial No. 838,643

before being admitted to the combustion chambers. As the fuel mixtureflows along this rather extensive path, raw fuel, in the mixture has atendency to drop out of suspension before the mixture reaches thecombustion chambers and,

, as a result, the predetermined balance of the mixture is disturbed. Itis well established in this art that the proportion of the fuel and airin the mixture is critical and a loss of fuel not only affects theperformance of the engine, but also reduces the eificiency of thelatter.

With the above in view, the present invention has as one of its objectsto reduce to a minimum the distance the fuel mixture is required totravel from the carburetor or mixing chamber to the of the engine. Inaccordance with this invention, an intake manifold for fuelmixture issupported on the engine in a position to supply fuel mixture directly tothe inlet ports formed in the engine cylinders adjacent the outer endsof the latter.

Another feature of this invention is to provide an internal combustionengine having a. cylinder block formed with a space directly oppositethe inlet ports in adjacent cylinders and having means on the intakemanifold coacting with a part of the engine block between adjacentcylinders to divide the space into twoindependent chambers.

Still another objector this invention is to provide an intake manifoldhaving a fuel mixture supply, passage communicating with the chambersadjacent the cylinders through branch passages and having resilientvalve members respectively secured thereto at opposite sides of thedividing means for controlling the flow of fuel cylinders mixturethrough the branch passages.

A further object of this invention is to provide an intake manifoldhaving wall portions at opposite sides of the dividing means which taperoutwardly from the dividing means so as to direct the fuel mixturelaterally throu hout the width of the chambers and having reed typevalve members respectively secured to the tapered wall portions fornormally closing the branch passages.

is admitted to the 4 Claims. (Cl. 123-43) The foregoing -as-well asother objects will be made more apparent as this description proceeds,especially when considered in connection with the accompanying drawings,wherein- Figure l is a side elevation of an internal combustion engineembodying; the features of this invention;

Figure 2 is a sectional view taken substantially on the plane indicatedby the line 2-2 of Figure 1;

Figure 3 is an end elevation, partly in section, of the internalcombustion engine shown in Figure 1;

Figure 4 is a end elevation of the intake manifold for the internalcombustion engine.

Figure 5 is a side elevation of the intake manifold shown in Figure 4; t

Figure 6 is a cross-sectional view taken substantially on the planeindicated by the line 8-6 of Figure 4; and

Figure 7 is a fragmentary sectional. view through a modifiedconstruction of intake manifold.

Referring first to the embodiment of the invention shown in Figures -1to 6 inclusive, it will be noted that the reference character l0indicates a multi-cylinder two cycle internal com-- bustion engine ofthe liquid cooled type. For the purpose of illustrating the presentinvention, a two cylinder engine is selected but it will be understoodas this description proceeds that. the invention is applicable tointernal combustion engines having more than two cylinders.

. With .the above in view, particular attention is directed to Figures 1to 3 inclusive of the drawings, wherein it will be noted that theinternal combustion engine i0 comprises generally a cylinder block I i,a crankcase l 2 and a cylinder head l3. The crankcase I2 is detachablysecured to the block Ii by means of studs l4 and cooperates with theadjacent portions of the block to form bearings I5 in which thecrankshaft i6 is journailed.

The cylinder head l3 forms a closure for the outer ends of the cylindersi'l, formed in the block H in juxtaposition to one another, and studsiii are provided for detachably securing the cylinder head to the block,In eccordance with conventional practice, a pair of combustion chambersiii are formed in the cylinder head and respectively register with thetwo cylinders [1.

Each cylinder is lined with a tube 20 formed of a wear resistingmaterial and a piston 2| is formed on the shaft IS in spaced relation toeach other axially of the shaft. One of the cranks is indicated inFigure 3 of the drawings by the reference character 22 and is arrangedapproximately 180 from the other crank (not shown), which is connectedto the piston in the next adjacent cylinder. to the respective cranks bymeans of rods 28 and the arrangement is suchthat when .one piston is onits suction stroke, the next adjacent piston is on its compressionstroke. It will be understood that when the pistons are moved on theirrespective suction strokes, fuel mixture is drawn into the crankcase.

As is usually the casein two cycle internal combustion engines, thecylinders are formed with inlet and exhaust ports which are controlledby the pistons in the cylinders. As shown in Figure 2 of the drawings,the cylinder block ii is formed with a space 24 opposite the cylindersi7 and this space communicates. with the interior of the cylindersthrough the medium of inlet ports 25 formed in the adjacent side wallsof the cylinder intermediate the ends ofthe latter. It' will also .benoted from Figure 2 of the drawings that the cylinder block H is formedwith a space 26 at the opposite sides of the cylinders I1 and this spacecommunicates with the interior of the cylinders through the medium ofexhaust ports 21. A cap 28 is removably secured to the cylinder block Iiand cooperates with the space 26-to form an exhaust manifold fordischarging the products of combustion out of the engine.

Fuel mixture is supplied to the space 24 by means of a carburetor 29 andan intake manifold 30. The carburetor 29 is of conventional constructionand serves to mix fuel and air in the proportions required to obtainefiicient operation of-the engine. The manifold 30 has a cylindricalbody portion 3i, which is sleeved in an opening 32 formed in the outerwall of the cylinder block opposite the inlet openings 2-5 and aradially outwardly extending flange 33 is formed on the body 3i forabutting engagement with the outer surface of the cylinder blocksurrounding the opening 32. An annular sealing gasket 34 is providedbetween the inner surface of the flange 33 and the adjacent surface ofthe cylinder block to prevent the escape of fuel mixture from the space24. Suitable studs 35 are provided for detachablyksecuring the manifold30 to the cylinder b no The inner surface of the manifold 30 is formedwith a diametrically extending rib 36 having a flat surface 31 whichcooperates with a corresponding flat face 38 formed on the block betweenadjacent cylinders I! to divide the space 24 into two chambers 39 and40. The surface to surface contact between the rib 36 and adjacent partof the cylinder block provides a seal which prevents the escape of fuelmixture from one chamber to'the other.

Referring now more in detail to. Figure 6 of the drawings, it will benoted that the manifold has a Venturi-shaped passage. which communicateswiththe carburetor to receive fuel mixture from the latter and is formedwith branch passages 42 and 43. The branch passages 42 and 43respectively communicate with the chambers 39 and 40 at opposite sidesof the dividing rib 36 on the manifold. In this connection, attention isdirected to the fact that the inner wall of the manifold tapersoutwardly from opposite sides of the rib 36 so that fuel mixtureentering the The pistons are connected.

chambers from the branch passages is directed laterally across thechambers.

The branch passages 42 and 43 are normally closed by reed type valvemembers 44 and 43. The valve members are in the form of spring metalstrips having corresponding ends ,secured to the manifold and having theopposite ends respectively overlapping the delivery ends of the branchpassages. The opening movement of the valves is restricted by means ofrigid backing members 48, which are also secured to the manifold. Asshown in Figure 4 of the drawings. the same fastener elements 4'! areemployed for securing the valve and backing members to the manifold.

The above construction is such that when the pistons 2| in the cylindersI! are in their respective suction strokes, the valves are opened by thesuction created in the chambers 39 and 40. As a result, fuel mixturefrom the carburetor 29 is admitted to the chambers and flows from thechambers through the inlet ports 25 into the cylinders. It is importantto note that the delivery ends of the branch passages in the manifoldare so closely related to the inlet ports 25 in the cylinders that thefuel mixture may be considered to pass directly from the intake manifoldinto the cylinders. This is highly desirable in that very littleopportunity exists for raw fuel to fall out of suspension from the fuelmixture before the latter is introduced into the cylinders. Thus, thefuel mixture introduced into the cylinders retains the specifiedproportions of fuel and air which are essential in order to obtainefiicient engine performance. 7

As the pistons 21 travel on their respective compression strokes, theproducts resulting from previous combustion of the fuel mixture arefirst discharged from the cylinders through the exhaustports 21 and thenthe fuel mixture is compressed in the combustion chambers l9. This fuelmixture is ignited by suitable spark plugs 48, which are secured to thecylinder head l3 in the usual manner.

The embodiment of the invention shown in Figure 7 of the drawingsillustrates a manifold 50 differing from the manifold 30 in that theinner wall of the manifold at opposite sides of the rib 33 is straightinstead of tapered, and the supply passage 5| is not provided with aventuri. The remaining structure is substantially the same as previouslydescribed and the same reference characters are used to indicatecorresponding parts.

It has previously been stated that the present invention is not limitedin its use to two cylinder engines. In this connection, it will be notedthat in the event it is desired to equip a four cylinder engine with thepresent invention, the manifold and corresponding parts previouslydescribed are merely duplicated for the other pair of cylinders. This istrue for each pair of cylinders added, and therefore, reservation ismade to incorporate the principles of this invention in internalcombustion engines regardless of the number of cylinders.

What I claim as my invention is:

1. An internal combustionengine having cylinders arranged adjacent eachother and having inlet ports for fuel mixture in one side wall of thecylinders, a block in which the cylinders are formed having a spaceopposite the inlet ports in said cylinders, an intake manifold extendinginto said space through the outer wall of the block and having anintermediate portion coacting with a part of the block betweenadjacentcylinders to divide said space into two bers, said manifold furtherhaving passages therethrough which respectively communicate with thechambers, and valve members on the manifold at opposite sides of .thedividing portion for controlling the flow of fuel mixture to saidchambers.

2. An internal combustion engine having cylinders arranged adjacent eachother and having inlet ports for fuel mixture in one side wall of thecylinders, a block in which the cylinders are formed having a spaceopposite the inlet ports in said cylinders, an intake manifold extendinginto said space through the outer wall of the block and having anintermediate portion coacting with a part of the block between adjacentcylinders to divide said space into two independent chambers, aVenturi-shaped passage in the manifold having the delivery endrespectively communicating with the chambers at opposite sides of thedividing portion through branch passages, and valve meansforindependently controlling the flow of fluid mixture through said branchpassages.

3. An internal combustion engine having cylinders arranged adjacent eachother and having inlet ports for fuel mixture in one side wall of thecylinders, a block in which the cylinders are formed having a spaceopposite the inlet ports in said cylinders, an intake manifold extendinginto said space through and having an intermediate portion coacting witha'partof the block between adjacent cylinders to divide said space intotwo independent chambers, a passage in the manifold respectivelycommunicating with said chambers at opposite sides of the dividingportion through branch passages, 9. Diston slidably supported in eachcylinder and operable to control said inlet ports, and resilient valvemembers respectively secured to the manifold at opposite the outer wallof the block' sides of the dividing portion for independent chami saidbranch passages.

4. An internal combustion engine having cyl- "inders arranged adjacenteach other and having inlet ports for fuel mixture in one side wall ofthe cylinders. a block in which the cylinders are formed having a spaceopposite the inlet;- ports in said cylinders, an intake manifoldextending into said space through the outer wall of the block and havingan intermediate portion meeting with a part of the block betweenadjacent chamberssaid manifold having walls at opposite sides of thedividing portion which taper outwardly from the dividing portion, es inthe manifold r espectively communicating with the chambersfthrough saidtapered walls, and resilient .valve members respectively secured to thetapered walls and normally closing said passages.

- JAY W. SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES Pxrnm's

